feat(nginx): allow custom nginx locations to be configured in the values

[spotzero]

I have a use case for needing a second location entry point from nginx into Drupal. I believe this could be accomplished transparently by making the nginx configuration configurable in a similar way to the Varnish config.

I think the following change is a reasonable and transparent way of adding that support, but I'd appreciate if someone could review the sanity of this approach :)

[sylus]

@spotzero this looks good to me can you do this for the drupal7 version and just bump the chart.yaml versions?

I will then merge!

[spotzero]

@sylus Updated :+1: